Manufacture and operation of vacuum tubes



Patented July 15, 1924.

KARL ROTTGARDT, OF DAHLEM, NEAR BERLIN, GERMANY.

MANUFACTURE AND OPERATION OF VACUUM TUBES.

No Drawing.

Application filed August 26, 1921.

Serial No. 495,601..

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT, L,1313.)

To all whom it may concern.

Be it lmown that I, Dr. KARL ROTTGARDT, residing at Dahlem, near Berlin,Germany, Fontanestr. 14, have invented certain new and usefulImprovements in and Relating to the Manufacture and Operation of VacuumTubes, for which application has been filed in the following countries:Germany, March 30, 1918; Denmark, June 15, 1920; England, July 9, 1920;France, July 2, 1920; Poland, July 2, 1920; Japan, Oct. 19, 1920; and Ido hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others 1 skilled inthe art to which it appertains to make and use the same.

It is well known in the process of manufacturing vacuum tubes having aplurality of metal electrodes, to bring the metal parts in the interiorof the tubes, and in particular the anodes, to incandescence by theapplication of high voltages. This is termed bombardment by electrons.In this way the last remnants of gas are removed from 25 the metal andthe highest vacuum considered necessary is produced.

This invention relates to a new improve ment in the manufacture andworking of such vacuum tubes. This improvement makes it possible toeffect the incandescence of the metal parts with considerably smallervoltages. At the same time the tubes treated in accordance with theinvention possesses the property, when in operation, of being able toreceive andrectify considerably greater anode charges with much smallervoltages. The new improvement consists in the feature that certain gasesor vapours, in particular ether vapour and also other easily volatilehydrocarbons are admitted into the tubes for pumping purposes.

It appears that, at the same temperature of incandescence of thefilament, quite a considerable increase in the thermionic currentresults when these vapours are admitted. This produces a greaterreceptive capacity of the tubes and thus a stronger heating of theelectrons results. The differences are of such a large order that, forexample, after admission of the gas a light red glow of the anodesoccurs at 300 volts, while before, no visible heating up occurred at1300 volts with the same incandescing current.

This great increase in the thermionic current is still maintained whenthe admitted gases or vapours have been again exhausted by the pump, sothat in operation also a considerable increase in efiiciency occurs.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed I declare thatwhat I claim is 1. The process of manufacturing vacuum tubes having aplurality of metallic electrodes, which consists in introducing ahydrocarbon vapor into the vacuum tube, applying across two of theelements thereof a voltage sufficient to raise at least one of theelements to 'incandescence, and evacuating the vacuum tube.

2. The process of manufacturing vacuum tubes having a plurality ofelectrodes, which consists in introducing ether vapor into the vacuumtube, applying a voltage across two of the elements thereof suflicientto raise at least one of the elements to inoandescence, and evacuatingthe vacuum tube. V

In testimony whereof I aflix my signature.

DR. KARL ROTTGrAQRD'l.v

